June 30, 2015: With the last day of June wrapping up dry, here are some unofficial totals for Rockford and the Stateline (of course, can’t be official until after midnight tonight).

Rockford, of all things, will end the month a hair below average.

Click on image to enlarge.

You are likely thinking “What?! But this month was so rainy!”. Yep, this month had the amount of rain that a typical June gets.

However, just because a weather sensor in Rockford records that amount, doesn’t mean it’s getting everything for the area. You can see how localized heavy rainfall can be on the following maps.

Total rainfall for June 2015 in Illinois. Click on image to enlarge.

This month, a lot of the heavy rainfall was concentrated on Lee County, and areas to the north and west. The strongest storms seemed to have fizzled out by the time they were crossing Winnebago and Boone Counties (the areas on blue and green vs purple). Some spots of Lee Co. had over 10″ of rain (in pink) this month!

How far above or below average rainfall was in June for Illinois. Click on image to enlarge.

This map shows how much above average 10″ of rain is, and we are looking at anywhere from 5″ to 8″ above average.

Good news moving forward: regardless of how much rain your area received, July will start out dry for a few days, giving everyone a chance to dry out after a rainy June.

June 25, 2015: Most of this month’s rain has fallen in the last two weeks. Some areas are pretty water-logged as a result, so hopefully the next few weeks lay off on the rain a little.

Surprisingly, Rockford is only slightly above average this month, overall.

Click on image to enlarge.

Including today’s rainfall, we reached the 4″ mark for the month. An average June has 4.65″, so we aren’t that far away at this point.

However, let’s zoom out from just one point in Rockford to see the rest of the Stateline over the last 2 weeks.

Rainfall from June 11 to June 25. Click on image to enlarge.

Areas west and south of Winnebago Co. have seen a lot more than 4″, and some sections of Lee Co. have picked up over 10″ of rain! That’s around two months’ worth of rain in 2 weeks.

How much “excess” rain has fallen in the last 2 weeks (June 11-25). Click on image to enlarge.

To put this in perspective, some areas picked up an extra 8″ of rainfall when compared to the typical amounts that fall from June 11 to the 25th!

These maps also show where a lot of the rain has tracked recently, and how widely ranging precipitation totals can be at times. It would be nice to have the rain as evenly distributed as possible, but that’s not always the case. The forecast over the next week doesn’t have any signs of heavy rainfall or constant showers, so we should get a breather for a while to dry out some.

June 24, 2015: As mentioned yesterday, there are plenty of time when one round of thunderstorms has a direct impact on the next rounds coming after them. This can have major impacts on possible severe weather; we may see plenty of potential for severe weather, but have to wait to see how the pieces fall into place.

Tonight, strong thunderstorms are still possible, but not as likely as areas south of I-80 in central Illinois. The reason for the shift in the severe weather areas is all do to earlier rounds of thunderstorms.

Click on image to enlarge

Several rounds of thunderstorms in Iowa this morning produced enough outflow to keep a warm front nearly stationary over Missouri. The air behind that front is very unstable and would be needed to help fire off severe weather over us. However, the morning storms in Iowa plus a little activity that rolled through the Stateline this evening has kept us nice and cool, and pushed on the front enough to keep it in place.

As a result, the best places for severe weather are now in southern Iowa and central Illinois, and away from us. We could still get some strong storms and heavy rainfall, which could lead to flash flooding, but the risk isn’t as high as to our south.

Click on image to enlarge.

Eventually, upper level winds will direct more unstable air towards us, so the strong storms in Iowa do eventually move in, but without the extra help from the warm front being close to us, we won’t see as explosive of development.

Keep the weather radio on and handy just in case overnight, and watch out for flooded roads tomorrow morning during your commute. However, we shouldn’t have to hold our breath as much tonight since conditions are looking better for severe weather in places that aren’t our backyard.

June 18, 2015: Tropical Storm Bill has been stirring up plenty of trouble with rain and wind since it made landfall in Texas earlier this week, and we may feel some of those impacts in our region. One of the advantages of living in the Midwest is NOT having to deal with tropical storms and hurricanes. However, every once in a while, one holds together just enough to provide the Midwest with a little rain.

Click on image to enlarge

You can see here that Bill started over the warm, moist air of the Gulf of Mexico, and made landfall this past Tuesday. Sustained winds were around 40 mph, but the wind gusts were in the 60 mph range. As Bill moves north, the storm will weaken, since the very warm and humid air of the Gulf won’t be feeding it any more. The storm essentially weakens into a strong low pressure system, similar to ones we get around here to bring us rain. What’s neat is that southern Illinois will be getting a taste of Bill this weekend! The storm will not be nearly as strong, as you can see.

Click on image to enlarge

While Bill brings blustery winds, the bigger impact is the rainfall Bill is able to provide. In fact, with most hurricanes and tropical storms, its not the winds that do the most damage, like you would think. It’s the rain and flooding this storms can create. You can see in the radar image from Thursday evening that numerous flash flood warnings are out (in maroon), though a few severe thunderstorm warnings are occurring too (in orange).

Click on image to enlarge

Here’s the 48-hour rainfall totals from the the stretch Bill has covered. This doesn’t capture all of the rain Bill has dropped, but you get a decent picture that these storms can drop a ton of soaking rain, especially since they move pretty slow (Bill is only moving north at 11 mph), allowing the heavy showers to sit on places until they are flooding. In fact, some areas in Texas saw 6″ to 10″ of rain, while in Oklahoma, certain areas had 4″ to 8″ of rainfall!

Bill will be much weaker by the time the storm reaches Illinois this Saturday, but a possible 2″ or more of rain may still fall as the weakening storm moves eastward. The Stateline should be a little too far north to get rainfall from Bill, though we may get to see some of the clouds streaming off the storm over our area, which is a neat bonus. It’s not often we get to say our weather is being influenced by a tropical system in these parts!

June 16, 2015: Today was nice, mostly due to the lack of rain! This was the first day in the last 6 that we are completely dry. 3 of the last 6 have also featured flash flood warnings in the Stateline because of the intense rainfall at times.

Rockford is now at 2.62″ of rain for the month, which is right on average for June. 2.29″ of that came within the last 5 days, which is why everything is so soaked. In some areas of the Stateline, 4 times the normal amount of rain for a week fell during this rainy stretch!

So, why so rainy lately? We’ve had a pretty good setup for that hefty amounts of rain. There’s a lot going on on this map, so bear with me:

3 main factors have lined up repeatedly for heavy rainfall:

1) First, plenty of moisture. The days lately have been very humid, with dewpoint temperatures in the 70’s! This means showers and storms have a lot of water that they can suck up and drop over our area. Stronger winds in the lower part of the atmosphere has been keep the very moist air flowing into the area.

2) Next, the jet stream is positioned perfectly to bring us a lot of chances for rain. Disturbances in the jet help spark up showers, and direct them right into the Stateline, since the jet is set up directly over us.

3) Finally, we’ve had a series of warm and cold fronts criss-cross the area. These boundaries are great for creating showers and storms. The problem is that they aren’t moving fast at all, allowing them to sit and pour over the same spot.

The combo of all three of these factors is like taking a garden hose and pointing it at one spot on the ground. Eventually, the ground can’t hold any more water, creating a large puddle because the stream of water won’t stop.

Looking forward into next week, while the jet stream looks to stay in place, we should more pushes of dry air out of the north, which should help keep the humidity a little lower and leave less fuel for heavy rain. Rain will continue to be on and off in the forecast, but at least the heavy rain risk will be lower.

A Tornado Watch is in effect for Boone, Carroll, DeKalb, Jo Daviess, Lee, Ogle, Stephenson, Whiteside and Winnebago County in northern Illinois until 7pm Monday. A Tornado Watch is also in effect for Green and Rock County in Wisconsin until 7pm.

Exactrack HD Doppler Radar: 3:30pm

A fast moving line of thunderstorms will barrel out of eastern Iowa for the late afternoon and in the the evening hours. The main threats with this line are strong, damaging wind gusts over 70mph, some hail, dangerous cloud-to-ground lightning, and very heavy rain. This line of storms is expected to reach the Rockford area just in time for the evening commute. Storms will likely exit the eastern half of our area just before sunset. Please keep an eye to the sky!

Be prepared to seek shelter as these thunderstorms are fast approaching. There is the possibility of some rotation in this line of storms….something that will have to be closely watched. Flash flooding is also a concern with the potential for a couple of inches of rainfall. Keep it tuned to the 13 Weather Authority for the latest information!

A nearly stationary frontal boundary is to blame for the heavy rain and flash flooding that affected a large swath of real estate in northern Illinois. Showers and thunderstorms developed along the front Wednesday evening through Thursday morning. Thunderstorm activity sustained itself over the same area for almost 12 hours!

The result was extremely heavy rain, some hail, and plenty of flooding. The hardest hit areas included much of western and southern Lee County, northern Ogle County, far eastern Whiteside County, Carroll County, and western Jo Daviess County. Creeks and streams have filled up and there is a lot of standing water in area farm fields.

Radar-estimated Rainfall

Isolated pockets of 4 to 6 inches of rain fell along the Route 72 corridor from near Lanark east to Monroe Center, including Shannon, Forreston, Byron, Stillman Valley and Davis Junction. The Dixon, Sterling and Rock Falls area picked up similar rainfall amounts. Southern Lee County—south of Amboy and Sublette—had radar-estimated rainfall totals greater than 8 inches!

More on the Way?!

Looking ahead to Thursday evening and overnight, more heavy rain is an unfortunate possibility across our region. Another couple of inches is not out of the question where heavier thunderstorms persist. -Joe

Similar Set-Up for Tonight

Local Rainfall Reports over 2 Inches

(observations are recorded by volunteers and submitted to the National Weather Service)

A Flood Watch is in effect for northwestern Illinois and southern Wisconsin through Monday morning. Our local Illinois counties under this watch include Carroll, Jo Daviess, Stephenson and Whiteside. Our local Wisconsin counties under a Flood Watch include Green, Rock and Walworth.

Flood Watch

Additionally, a Flood Watch is in effect for the Kishwaukee River in southern Winnebago County for possible rising water early this week. Periods of rain with embedded thunder will continue through Sunday afternoon, evening and overnight. Rain will be heavy at times, especially in the evening and nighttime hours.

Weekend Rainfall through 3pm Sunday

Local rainfall totals from Saturday through early Sunday afternoon have varied across the area, with Rockford picking up about half an inch. Parts of Jo Daviess County and much of southern Wisconsin have seen their rain gauges add up to nearly an inch.

Additional Rainfall Potential through Monday Morning

Additional rainfall of one to two inches is possible overnight through early Monday morning.

Most of the United States is relatively safe when it comes to severe weather. Of course, we think of Oklahoma and Texas as being prime spots for tornadoes. But a new map shows us the average amount of time spent in a weather warning per county. Daryl Herzmann of Iowa State University released some great maps this week. Take a look!

First, here is the average time spent in a Severe Thunderstorm Warning.
Of course, the higher likelihood for severe thunderstorms lies in the Tornado Alley state of Oklahoma. But notice the maximum over Eastern Tennessee and even Northern Ohio. It may be a little difficult to see the actual location of states because the dark black lines in this map represent the borders of the National Weather Service offices. Here in Northern Illinois and Southern Wisconsin, we are serviced by three different offices, Milwaukee-Sullivan, Quad Cities-Davenport, and Chicago-Romeoville.

Next up, the map showing the average minutes of the year spent in a Tornado Warning:

A few things on this map stand out. First, the larger counties within a tornado-prone zone have a higher chance of being within a warning polygon. Of note is the number of minutes in McLean Co., IL (Bloomington-Normal) which is the largest county in Illinois in bright red compared to Putnam Co., IL (North of Peoria) which is blue.

Daryl went further and took square kilometers into account with the following map. This one is telling! It shows the highest likelihood of a Tornado Warning (not necessarily a full-fledged, on-the-ground tornado) to be in Mississippi.

So, while we may think of Tornado Alley being Texas and Oklahoma, the higher threat of tornadoes may reside in the Deep South…at least looking at the data over the past 20 years.

Finally, for your viewing pleasure? The map for Flash Flood Warnings per county. It’s easy to see the highest probabilities for flash flooding in the past 20 years are in Southern Missouri and in the Desert Southwest.

Even though we’ve got chilly temperatures for the next day or so, minor flooding will cause a few headaches this week. As the ground thawed out and much of our snowpack melted off last week, area creeks and rivers have been on the rise. Luckily, we’ve had a slow thaw and very little rain to agitate our waterways. Nonetheless, creeks and rivers have filled their banks in many spots, even flowing over their banks in others.

Washed out road in Ogle County

As the ice continues to break up, ice jam flooding will be a concern. Ice jam flooding can last a short amount of time or several hours and often comes with very short notice.

Ice jam along the Rock River

Flood warnings and advisories are posted for the Rock River in Ogle, Lee & Whiteside County. Minor flooding is also occurring along the Pecatonica River in Winnebago & Stephenson County. Smaller rivers and creeks have also been affected, including Turtle Creek near Beloit, Yellow Creek near Pearl City and Killbuck Creek near Lindenwood.

Minor flooding is forecast

The National Weather Service offers river gauge and water level data for waterways throughout our region. Click on these links to monitor your local creeks and rivers: